Cartridge-fuse



L. 'F. KRIES. CARTRIDGE FUSE. APPLICATION FILED AUG. I6, 1918.

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LAWRENCE F. KRIES, OF BALTIMORE, MARYLAND, ASSIGNOR T0 CHARLES MORGAI'TMARSHALL, TRUSTEE, OF BALT IMOBE, MARYLAND.

CARTRIDGE-FUSE.

Specification of Letters Patent. Patented Sept. 14, 1920.

Application filed August 16, 1918. Serial No. 250,186.

To all whom it may concern.

Be it known that I, LAWRENCE F. Kniss. a citizen of the United States,residing at Baltimore, State of Maryland, have invented certain new anduseful Improvements in Cartridge-F uses, of which the following is aspecification.

This invention relates to thermal cut-outs for electric circuits, andmore particularly to cut-outs of the cartridge fuse type.

It has been found in practice that in many cases where ordinary fusesare emwill often replace such a fuse by a fuse of too great a capacityor-even by a piece of wire, either to avoid the necessity of replacingburned out fuses or else for the purpose of obtaining a greater currentthan the circuit was designed to carry.

In order to more effectually limit the carrying capacity of a circuitand prevent re-fusing in an improper manner, the object of the presentinvention is to provide a cut-out device in the form of a cartridge fusecontaining two separate fusible elements, one of which is accessible andcan be renewed in the ordinary way, and the other of which isinaccessible or non-replaceable without destroying the cut-out. Thisaccessible or non-accessible fusible element has a carrying capacitygreater than the ordinary or replaceable element, but small enough tolimit the current in the circuit to a safe figure.

In order that the invention may be readily understood, reference is hadto the accompanying drawing forming a part of this specification and inwhich,

Figure 1 is a longitudinal section of a cartridge fuse embodying theprinciples of my invention;

Fig. 2 is a similar view taken on a plane at an angle of ninety degreesto that of Fig. 1, and

Fig. 3 is a transverse section on the line 3-4-3 of Fig. 1, looking inthe direction of the arrow.

Referring now to the drawings in detail, my improved cartridge fusecomprises two separate sections 1 and 2 preferably separa bly united asby means of screw threads 3. The section or compartment 1 is closedatits ends by means of a disk 4, held in position by a screw-cap 6. havinga flange 5. in order to prevent rotation of the disk 4 it is providedwith portions adapted to interlock with notches 7 formed in the end ofthe casing 1.

Extending through the disk 4: is the usual or any suitable blade 8constituting one terminal of the cut-out, and adapted to be receivedbetween spring clips, in the well known manner. To the inner end of theblade 8 ,is secured a bar of insulting material 9 carrying at its otherend a metal 'clip 10 and between the clip 10 and the blade 8 extends theordinary replaceable fuse 11, secured by means of screws 12. Othermethods of supporting this fuse may he employed without departing fromthe spirit of the invention.

The other section 2 of the casing carries at its inner end a spring-clip13 adapted to receive the clip 10 above described. This clip 13 iscarried by a disk or partition wall 14 which is permanently secured inthe end of the section 2 in any suitable way, and

held in position by ineansof an annular flange or shoulder 15. Anonreplaceable fuse 17 is secured at one end to the clip 13 as by meansof a screw 16 and its other end is carried through an opening in a metalcap 19 which is secured to the casing 2. This cap 19 is permanentlyattached to the casing as by means of crimping, as indicated at 19. Theend of the fuse 17, after passing through the cap 19 is cut off and maythen be secured to the cap by fusing the end with a soldering iron orthe like, so as to form a head or bead 18, as clearly shown in thedrawing. A blade 20 is secured to the cap 19 in any suitable way, andconstitutes the other terminal of the cutout.

It will be understood that the parts 1, 2, 4 and H are formed of anysuitable insulating material such as hard fiber, or the like.

From the above description it will be obvious that by unscrewing the cap(3, the disk 4 and the attached blade 8, bar 9 and clip 10 may bewithdrawn from the casing 1 so as to afford access to the fuse 11 forinspection or renewal. It will also be seen. that the fuse 17 isentirely concealed within the permanentlyclosed compartment 2, so

should be separated by unscrewing at the point 3. The fuse 17 is ofgreater carrying I capacity than the fuse 11, but is still small enoughto blow with a current which the circuit can carry safely. If,therefore, an unscrupulous or ignorant person should undertake toreplace the fuse 11' with a larger one or with a? piece of wire, itWould still be impossible for him to draw from the mains current inexcess of that which the fuse 17 will carry, which fuse, therefore,serves to determine the maximumcurrent Which'the cut-out will stand andto limit such current to a safe figure.

It will be seen that my improved device, being in the natureof acartridge fuse, is simple in construction and cheap to manufacture, andit is thought that its many advantages will be readily appreciated bythose skilled in such matters.

If desired, the head 14 may be made of brittle material, or materialwhich cannot be readily bored through, so that a wire or heavy fusecannot be passed through the heads 19 and 14, when the part 1 isremoved, and soldered or otherwise connected to the part 13, outside thehead 14. If a fuse were so connected it would be concealed when thecasing is assembled.

l/Vhat I claim is:

' 1. A cartridge fuse comprising an elongated casing divided by atransverse partition into two compartments, a fuse in each compartment,said fuses being of different carrying capacities and connected inseries,

a portion of the casing forming one compartment being readily removableto afiord access to the fuse in that compartment, and the compartmentcontaining the other fuse being sealed against opening except bydestroying the casing.

2.'A cartridge fuse comprlsln'g an elongated casing divided by atransverse part1- tion into two compartments, a fuse in each compartmentbeing sealed against opening except by destroying the casing.

3. A cartridge fuse comprising a casing having a contact terminal ateach end thereof, said casin being divided into two compartments, a usein each compartment connected with its respective contact terminal, saidfuses being of different carrying capacities and connected in series,the compartment containing one fuse being sealed against opening exceptby destroying the casing, its associated contact terminal and anadjacen't portion of the casing being readily separable as a Whole fromthe sealed compartment, to afford access to said second mentioned fuse.

In testimony whereof I affix my signature.

LAWRENCE F. KRIES.

and the second fuse, together with

